Thermodynamics of Heat Shock Response

TL;DR

This paper investigates the thermodynamics of heat shock response in E. coli, showing how protein stability influences heat shock magnitude and suggesting a thermodynamic basis for protein folding control.

Contribution

It demonstrates a quantitative link between protein stability and heat shock response, proposing a minimal chemical network model for this biological process.

Findings

Reversed heat shock observed at low temperatures.

Heat shock magnitude correlates with protein stability.

Thermodynamic stability explains heat shock behavior.

Abstract

Production of heat shock proteins are induced when a living cell is exposed to a rise in temperature. The heat shock response of protein DnaK synthesis in E.coli for temperature shifts from temperature T to T plus 7 degrees, respectively to T minus 7 degrees is measured as function of the initial temperature T. We observe a reversed heat shock at low T. The magnitude of the shock increases when one increase the distance to the temperature $T_0 \approx 23^o$, thereby mimicking the non monotous stability of proteins at low temperature. Further we found that the variation of the heat shock with T quantitatively follows the thermodynamic stability of proteins with temperature. This suggest that stability related to hot as well as cold unfolding of proteins is directly implemented in the biological control of protein folding. We demonstrate that such an implementation is possible in a minimalistic chemical network.